I was late to Pet Sounds but I now love the album. I was also lucky enough to see Brian Wilson on his Smile tour last year in the UK. It was one of the best gigs I've seen. Just fantastic.
I last heard this album when it was "required listening" for my History of Rock n Roll course in college. I think it's time to hear it again.
On a related note, I saw an interview in which Tony Banks of Genesis was commenting on Beach Boys' music. He said that they all sound quite simple....until one tries to play those songs, then their complexity reveals themselves.